1. Field of the Invention
The present invention relates to cationized hydroxyalkylcelluloses which are useful as components of shampoos, rinses, treatments, etc. and a process for producing the same.
2. Prior Art
Cationized hydroxyalkylcelluloses are known as components of shampoos, rinses, treatments, etc., since they contain quaternary ammonium groups as substituents. When employed as components of shampoos, rinses, treatments, etc., these cationized hydroxyalkylcelluloses should be highly compatible with surfactants which are employed as the principal components therein.
As a process for the production of cationized hydroxyalkylcelluloses, JP-B 45-20318 has disclosed a process comprising using cellulose as the starting material, adding an etherifying agent and a cationizing agent successively or simultaneously thereto and thus effecting a continuous reaction. However, this process is not advantageous economically, since the etherifying agent and the cationizing agent are each utilized only at a poor efficiency. Moreover, there arises another problem that it is highly troublesome to eliminate the unreacted materials and impurities formed in large amounts as by-products.
Meanwhile, JP-B 59-42681 has disclosed a process with the use of an ethylene oxide derivative or a propylene oxide derivative of cellulose as the starting material. Although a cationizing agent can be utilized at a high efficiency in this process, it is necessary in this process to react and wash again a cellulose ether which has once reacted and washed, i.e., the reaction and washing should be performed twice. In this process, a solvent mixture of isopropanol with water is used as a reaction solvent in most cases. When, however, the obtained product has a high degree of hydroxylalkyl-substitution, it is dissolved in the above reaction solvent. As a result, it becomes difficult to stir the reaction system due to the increased viscosity, which brings about a decrease in the conversion.
Further, in the prior art, there has not been developed so far any process by which the above-mentioned problems can be solved and cationized hydroxyalkylcelluloses having a high compatibility with surfactants can be constantly supplied.
An object of the present invention is to provide cationized hydroxyalkylcelluloses which are highly compatible with surfactants and useful as components of hair care products such as shampoos.
Another object of the present invention is to provide a process for producing these cationized hydroxyalkylcelluloses.
The present invention provides a cationized hydroxyalkylcellulose having a glucose unit represented by the following formula (I): 
wherein R1, R2 and R3 represent hydrogen atom, a group represented by the following formula (II): 
wherein R4 represents hydrogen atom or methyl; and xe2x80x9caxe2x80x9d is a number of from 1 to 6 on the average, or represented by the following formula (III): 
wherein R4 represents hydrogen atom or methyl; xe2x80x9caxe2x80x9d is a number of from 1 to 6 on the average; R5, R6 and R7 are the same as or different from each other and represent a C1-16 alkyl; X represents a halogen; and xe2x80x9cnxe2x80x9d is a number of from 50 to 2,000, the cationized hydroxyalkyl cellulose having a mobility distribution (xcex94U), determined by electrophoresis, in the range of from 0.1xc3x97105 10xe2x88x925 to 2.0xc3x97105 10xe2x88x925 cm2/secxc2x7V, including the above shown group (III) to have a nitrogen atom content (%) of from 0.1 to 10. 0.
The present invention further provides a process for producing a cationized hydroxyalkylcellulose, comprising the steps of mixing a hydroxyalkylcellulose with an aqueous solution of isopropyl alcohol or an aqueous solution of t-butyl alcohol; adding an alkali to the mixture; effecting cationization; and effecting neutralization.
The cationized hydroxyalkylcellulose of the present invention is one represented by the formula (I) wherein R1, R2 and R3 represent hydrogen, a group represented by the formula (II) or another group represented by the formula (III).
It is preferable that the substituent represented by the formula (II) has an average degree of substitution per glucose unit ranging from 0.4 to 2.9 and an average mole number ranging from 1.0 to 7.0. It is still preferable that the substituent represented by the formula (II) has an average degree of substitution per glucose unit ranging from 0.7 to 2.1 and an average mole number ranging from 1.6 to 3.6.
Although the upper limit of xe2x80x9caxe2x80x9d in the substituent represented by the formula (II) is not specified theoretically, it is preferable that xe2x80x9caxe2x80x9d ranges from 1 to 6 on the average.
The substituent represented by the formula (III) has an average degree of substitution per glucose unit ranging from 0.1 to 3.0, preferably from 0.1 to 1.5 and still preferably from 0.1 to 0.9.
Although the upper limit of xe2x80x9caxe2x80x9d in the substituent represented by the formula (III) is not specified theoretically, it is preferable that xe2x80x9caxe2x80x9d ranges from 1 to 6 on the average.
In the substituent represented by the formula (III), R5, R6 and R7 are the same as or different from each other and represent a C1-6 alkyl, preferably methyl or ethyl.
In the formula (I), xe2x80x9cnxe2x80x9d represents a number of from 50 to 2,000, preferably from 50 to 1,500. Examples of the halogen represented by X in the formula (I) include chlorine, bromine and iodine.
The cationized hydroxyalkylcellulose represented by the formula (I) has a mobility distribution (xcex94U) determined by electrophoresis of from 0.1xc3x97105 10xe2x88x925 to 2.0xc3x97105 10xe2x88x925 cm2/secxc2x7V, preferably from 0.1xc3x97105 10xe2x88x925 to 1.5xc3x97105 10xe2x88x925 cm2/secxc2x7V. By regulating xcex94U to be within the range as specified above, the compatibility, of the hydroxyalkylcellulose with surfactants can be elevated.
It is preferable that the cationized hydroxyalkylcellulose represented by the formula (I) has a nitrogen atom content (%) of from 0.1 to 10.0, still preferably from 0.5 to 4.0.
It is preferable that the cationized hydroxyalkylcellulose represented by the formula (I) has a degree of substitution a quaternary nitrogen-containing grout) of from 0.1 to 1.5, still preferably from 0.1 to 0.9.
Moreover, it is preferable that the cationized hydroxyalkylcellulose represented by the formula (I) has a viscosity at 25xc2x0 C. of from 30 mPaxc2x7s (as a 2%, by weight aqueous solution; 30 rpm) to 5,000 mPaxc2x7s (as a 1% by weight aqueous solution; 30 rpm), still preferably from 70 mPaxc2x7s (as a 2% by weight aqueous solution; 30 rpm) to 2,500 mPaxc2x7s (as a 1% by weight aqueous solution; 30 rpm).
Next, the process for producing the cationized hydroxyalkylcellulose of the present invention will be illustrated. Since the production process of the present invention is characterized by the type and concentration, of an organic solvent solution employed in the reaction, it is not particularly restricted in other treating procedures and conditions. That is, the present invention also involves in its scope any usual modification made by those skilled in the art in producing cationized hydroxyalkylcelluloses.
In the first step, a hydroxyalkylcellulose is mixed with an aqueous solution of isopropyl alcohol or an aqueous solution of t-butyl alcohol.
The hydroxyalkylcellulose to be used in this step can be obtained by a conventional method comprising, for example, treating cellulose with an alkali and then adding an alkylene oxide thereto. As the cellulose employed a the starting material use may be made of cotton linters, wood pulp, etc.
As the aqueous solution of isopropyl alcohol, it is preferable to use one having an isopropyl alcohol concentration of from 75 to 90% by weight, still preferably from 80 to 90% by weight. As the aqueous solution of t-butyl alcohol, it is preferable to use one having a t-butyl alcohol concentration of from 70 to 85% by weight, still preferably from 75 to 85% by weight.
It is preferable that the aqueous solution of isopropyl alcohol or the aqueous solution of t-butyl alcohol is employed in an amount of from 300 to 900 parts by weight per 100 parts by weight of hydroxyalkylcellulose.
In the second step, an aqueous solution of an alkali serving as a catalyst is added thereto. Examples of the aqueous solution of an alkali include aqueous solutions of sodium hydroxide and potassium hydroxide.
It is preferable that the alkali is used in an amount of from 0.05 to 0.4 times by mole as much as the glucose unit in the hydroxyalkylcellulose.
In the third step, cationization is effected by adding a cationizing agent. Examples of the cationizing agent to be used in this step include glycidyltrialkylammonium halides such as glycidyltrimethylammonium chloride, glycidyltriethylammonium chloride and glycidyltrimethylammonium bromide.
It is preferable that the cationizing agent is used in an amount of from 0.2 to 2.0 times by mole as much as the glucose unit in the hydroxyalkylcellulose.
In the subsequent fourth step, hydrochloric acid, sulfuric acid, etc. is added to thereby neutralize the alkali added in the above third step.
If necessary, the reaction product is purified by appropriate procedures, for example, washing with an organic solvent such as isopropyl alcohol or acetone and dried to give the cationized hydroxyalkylcellulose of the present invention.
The cationized hydroxyalkylcellulose of the present invention are useful as components of shampoos, rinses, treatments, etc.